Many agents such as medicaments and agricultural chemicals utilizing an optically active compound as an active ingredient are known. A number of methods are known as methods for preparing optically active compounds. Among them, the catalytic asymmetric synthesis technique is one of extremely powerful means. Since transition metal complexes having optically active phosphine as a ligand have superior catalytic activity and stereoselectivity for the catalytic asymmetric synthesis, they are also applied to industrial manufacturing processes (CATALYTIC ASYMMETRIC SYNTHESIS, Ed., Iwao Ojima, Wiley-VCH, 2000).
As optically active ligands which can form asymmetric catalysts, phosphine ligands and phosphorane ligands are known. As the phosphine ligands, for example, BPPM, BINAP, DIOP and the like are known, and as the phosphorane ligands, DuPHOS, BPE and the like are known. Although many of the phosphine ligands except for BINAP can be used for asymmetric hydrogenation of acetamidoacrylates, many of the ligands have rather narrower applicable range for other substrates. Moreover, they have problems in industrial application, for example, the synthetic route is long and each enantiomer cannot be obtained easily. The phosphorane ligands are reported to have characteristics not possessed by the conventional phosphine ligands, and to be excellent asymmetric hydrogenation catalysts (WO93/01199 (DuPHOS), WO91/17998 (BPE)). However, in order to form a phosphorane ring, an expensive optically active 1,3- or 1,4-diol is needed, and in addition, Et-DuPHOS, Et-BPE, Me-BPE and the like are oily substances and therefore have problems of susceptibility to oxidization and difficulty in handling.
(In the formulas, Me represents methyl group, and Et represents ethyl group.)
It is reported by Achiwa et al. that the phosphine ligand, PPCP, having a cyclopentane structure and forming a 6-membered ring chelate is fixed in the Skew arrangement and has superior stereoselectivity (Synlett, 49, 1991). However, it is difficult to modify the cyclopentane structure in the synthetic route in which a beta-ketoester compound is asymmetrically reduced with BINAP-Ru, and the resultant ester is reduced with a hydride. It is not easy to design and use an suitable ligand depending on a given substrate.
Although a catalyst having a cyclopentane structure is also disclosed in Japanese Patent Unexamined Publication (Kokai) No. 2005-336181, the asymmetric hydrogenation reaction characteristic to the present invention is not described.